The purpose of this study is to investigate how the addition of a new emulsion artificial tear to the tear layer of dry eye and normal patients affects aberrometry, contrast sensitivity, and reading ability over time. Previous studies have indicated that daily use of artificial tears over a two week period decreases the short term affect of drop application on aberrometry and contrast sensitivity measurements. The present study will examine the effects of 4 weeks of artificial tear use to determine when the responses stabilize.